Lock-stitch sewing machine



June 4, 1929.

LOCK STITCH SEWING MACHINE M. r. DENNE' Filed June 19, 1924 5 Sheets-Sheet 1 up f a; a? 11/ f2 113 o (m f (15 f lb 1P2 10 as L (:25 335 810 Ch m mrm MM? June 1929- M. T. DENNE LUCK STITCH SEWING MACHINE 5 Sheets-Sheet Filed June 19, 1924 June 4, 1929.

M. T. DENNE LOCK STITCH SEWING MACHINE Filed June 19, 1924 '5 Sheets-Sheet June 4, 1929. M. T. DENNE 1,715,822

LOCK STITCH SEWING MACHINE Filed June 19, 1924 5 Sheets-Sheet 4 Fig.3.(t0nt).

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June 4, 1929. M. r. DENNE LOCK STITCH SEWING MACHINE Filed June 19, 1924 -5 Sheets-Sheet Patented June 4, 1929.

UNITED STATES 1,715,822 PATENT OFFICE.

MARK THOMAS DENNE, OF LONDON, ENGLAND.

LOCK-STITCH SEWING MACHINE.

Application filed June 19, 1924, Serial No. 721,134, and in Great Britain June 19, 1923.

This invention has reference to improvements in and'rclating to lock-stitch sewingmachines of the type having a rotary horn through which the needle thread from a source of supply passes to a. whirl in the nose of the horn, and the barbed end of a-needle, reciprocated by mechanism located above the horn, passes through the work and the Whirl to receive the needle thread and then pull a loop of it up through the work to receive the shuttle thread, the stitch being finally set by a main take-up.

The main object of my invention is to provide a machine of the type referred to that can be run at a much higher speed than any heretofore put to the test of actual use.

Notwithstanding that a demand has for a long time existed for a machine of the type referred to that can successfully be run at a considerably higher speed than those in actual use, and that various attempts have been made to produce such a machine, the demand until now has not been met.

This matter has for a considerable time had my attention and I believe I have so far succeeded that I am able to construct such a machine that as regards speed of running is a very considerable advance onanything heretofore accomplished. Machines constructed by me according to the present invention and put to severe practical tests most certainly bear out the favorable opinion I have expressed.

The problem has not been easily solved because so many factors have to be borne in mind, that is to say the mechanism mustbe as simple as is reasonably possible; the rapidly moving parts, and in particular those having reciprocating movement, should be light and yet amply strong; side strains must be avoided; the needle thread should be supplied in as nearly as may be a direct or straight path from the source of supply to a point adjacent to the main take-up and again in as nearly a straight path as possible from this multiplicity of bends; the shuttle should be continuously rotated; the presser foot should adapt itself to variations in the thickness of the Work; the work feeding means must easily be adjustable for varying the length of the stitch, andwhat is of course very important-the take-up must set the stitch firmly.

The greatest difiiculty perhaps to be over come having regard to smoothness of working of the mechanism more or less directly involved is to set the stitch firmly whilst the machine is driven at high speed. This is mainly due to the fact that-other things equal-if a lon! length of thread is to be sub ected to a given considerable final tension or stress as is thecase when the needle loop is pulled to set the stitch there is considerably greater risk of breaking the thread if the thread were subjected suddenly to such final stress than when a shorter thread is so acted on. Indeed one of the reasons why machines heretofore in use cannot be run at the desired high speed is that the length of thread between the main take-up and the whirl is fairly considerable.

One of the important features of my invention is a stitch setting mechanism that not only is of simple construction; requires little power to actuate it, and is little subject to wear, but of which the principal ele ment viz a main take-up lever is located Within the horn itself so that its acting end is brought comparatively near the whirl.

That the desirability of having the main take-up as near as possible to the whirl is realized, is evidenced by the fact that it has been proposed to carry the roll on an arcuate slide carried by an arcuate bearing within the horn and which slide is reciprocate'd in the bearing by a system of levers attached to an end that projects beyond the hearing, but such a construction introduced defects that more than counterbalance the advantage of having the main take-up near the whirl, great as this advantage is. With such a construction it would not be possible to run the machine at a higherspeed than those in use;

Another important feature of my invention is that the needle thread is guided in a rectilineal path from the source of supply, or at any rate from the thread lock to a point adjacent to an auxiliary take-up and which 1s co-axial with the horn. Also that the thread after leaving the main-take-up is subject to a single bend. which forms a very obtuse angle.

Further important features of my invention-will be hereinafter described.

A machine of the type referred to embodying my invention is illustrated in the accompanying drawings wherein Fig. 1 1s aslde elevational view of the complete machine, this illustration being on a. smaller scalethan the other views. Fig. 2 is a half sectional new of the head of the machine showing the mech anism for operating the needle, the shuttle and the work feed-foot and also the driving and stopping mechanism; Fig. 3 shows in three parts, mainly in section the horn and the related parts; Fig. 4 is a front view of the wax-pot; and Fig. 5 is a front elevation of the head and other i'nechanism carried by it;

Referring to Fig. 1, the head a is carried by a pillar 7) to which is secured the hornsocket c, the pillar being supported by a tripod (Z.

Referring now to Figs. 1, 2, and 5, the head a is provided with bearings a to carry the cam shaft (L The means for driving said shaft will be described later on.

On a suitable part of the cam shaft on is mounted a face cam a in a cam groove in which the cam roll a having a stud a is engaged said stud supporting the needle bar.

a, to the lower end of which the usual barbed needle is secured, the dimensions and dispositions of the parts being such that as the cam shaft a rotates, the needle will be vertically vibrated, it being made to pass through the work (placed on the horn) and to pass through this into the whirl in the nose of the horn there to receive the needle thread and to pull a loop of this up through the work to the loop being engaged by the shuttle, in the well known manner.

The shuttle a is driven so that it rotates twice for every up and down movement of the needle and it is made to vibrate laterally towards and from the needle, its movement being so timed that when the needle has ascended and presents its loop of thread the chisel pointed hook of the shuttle will engage with the loop and deal wit-h it in the usual manner, after which the shuttle recedes from the needle to make its second revolution whilst the needle is about its lowermost position. By this means intermittent rotary motion of the shuttle is avoided.

For the said purpose the shuttle (L is carried by a slide a carried on a slideway formed or provided on the frame a so that it may be reciprocated horizontally for the purpose stated. The slide a is actuated. by a cam o that engages a roll on the lever a, a second roll on which engages a slot a in the slide so that, as the cam a rotates, the slide a and with it the shuttle will be moved towards and from the needle.

The shuttle revolves in a race one bearing of which is shown at a a"; and to rotate the same there is provided a gear o on the cam shaft 6& which meshes with a carrier or intermediate gear a that, in turn, actuates a bevel gear a which is in mesh with a similar gear on the shuttle driver shaft a" to rotate the driver (4 which is coupled in the usual manner with the shuttle. The ratio of the gearing is such that the shuttle rotates twice per revolution of the cam shaft (f.

The shuttle is provided with a holder for the thread cop a fitting into a recess on its face, said cop holder being retained in position and prevented from rotating by the stop a on the gate a. The latter is adapted to be opened to permit insertion and removal of cops as may be required.

To serve as a prcsser foot and also as a work feed, I provide a presser a that is formed with feed points and to which a four motion movement is in'iparted. For this purpose the following mechanism provided.

The presser a is carried at the lower end of a swinging bar (6 adapted to move between the front face of the head (L and a plate a. At its upper end a spring (L25 is provided that tends to press the feed point or presser into firm engagement with the work. At its lower end the spring is provided with a pad 0? that engages or contacts with a link a which at its lower end engages with the bar a. The bar (4 is pivoted at (L28 to a lever fulcrumed at a and having a long arm a on which is mounted asegment (L the inner edge of which is formed with teeth and hav inc a handle for hand operation as will be described.

Supported in a bearing coaxial with (19 is a cam lever a a roll on which. engages a cam groove 66 'n a cam a mounted on the cam shaft a Said cam lever has an arm a in which slides a bar a carrying a detent a that is adapted to be engaged with the toothed segment e The bar a is moved, so as to engage and disengage the detent (1 with the toothed segment (2 by an edge" cam cut on the cam disc a which acts on a roller a Said roller is carried by a lever on pivoted at a and connected by a. link a with the bar a The cams are so timed that the detent is moved to engage the toothed segment, raise this latter so as to lift the presser and feed foot, then disengage from the segment to permit the spring (L to depress the parts and cause the presser firmly to engage with the work whatever its thickness, and finally return the detent and its support to their initial position there to engage again the toothed segment and thus lock the presser against vertical movement. By the foregoing the required up and down movement of the bar (1 and presser (r are obtained. If desired the operator may at any time raise the presser by means of the hand lever referred to.

For imparting to the bar (Z23 (and therefore to the feed foot a) the necessary move I ments in the horizontal direction so as, in conjunction and timed relation with its vertical movements, "to obtain the desired four motion feed movements, the following mechanism is provided.

A lever a, dependent from a suitably sup ported shaft (0, carries a link (L43 that is connected to the bar a so as to permitsaid bar to move in the vertical direction. The shaft a is rocked by means of a slotted lever a that has a slot in which a block a is adjustably mounted. The said block is provided with a pin (4 that engages in an aperture in a block (0 that is mounted in a slot in a mu operated lever a which is pivoted at a to the head a. The lever a carries a cam roll a that engages in a cam race at so that as the cam shaft (6 rotates, the lever a is rocked and through the pin 60" imparts horizontal to and fro movement to the bar a and the feed foot (6. The blocks a and a may together he set up or down so as to vary the extent of the rocking movement of the lever (0 and. thus to a similar extent vary the amount of the feed movement of the feed foot a. After the said blocks have been adjusted they are secured in adjusted position by a set screw a that serves to clamp the block a in the slot of the lever a.

If desired the feed foot may be made to be movable relative to a presser foot on which it is carried so thatand this applies more especially to work in which stitches are to be in a groove as is the case for instance in outsole stitching of boots and shoeswhen the presser foot is lifted off the work and is being moved to a new position preparatory to the work being again fed forward, the feed foot or dog will remain in the groove though not exerting appreciable pressure thereon and will thereby serve as a work guide to facilitate the proper presentation of the work, more particularly if the stitchingis to be effected along a comparatively sharp curve as for instance at the toe portion of boots and shoes, to ensure the stitches being made to lie at the bottom of the groove even when the machine is running at what would be considered high. speed. For this purpose the feed dog may be carried by a spring plunger that has limited vertical or substantially vertical movement in the presser foot or its shank, or it may be pivoted to the foot. In either case it must move easily over the work when the presser foot having been raised, is moving to the new position as aforesaid, whereas when the presser is again made to the work, the feed foot or point must also be pressed into firm engagement with the work and the presser and feed point must then move as though made in one piece so as to feed forward the work.

In order that the work may be held firmly down as the needle draws the thread loop through the work, I may provide the presscr with an extension of a length about equal to the longest stitch within the compass of the machine.

I now propose to describe the means for rotating the whirl and the needle thread guiding and controlling means, all of which are illustrated in Figs. 1, 2 and 3.

The horn e is secured on a table 0 that has a trunk which at its upper and lower ends is provided with ball bearings e and 0 respectively so that it may freely rotate within the socket c. The horn is of unusual construction in that its lower part which is of greatest diameter (as is usual) is of much greater depth than has heretofore been. found necessary. This improvml form is given to the horn so that itmay accommodate a main takeup of improved construction and arrangement and by the use of which much improved results as regards speed Of opera tion of the machine may be obtained.

The top end or nose of the horn contains the usual whirl, which it not necessary to illustrate, and which whirl is driven by the usual operating shaft a that derives rotary motion from the cam shaft a through the intermediary of mechanism now to be ,described.

On the cam shaft a I secure a bevel wheel (L52 that meshes with a bevel wheel a fixed on the upper end of a vertical shaft a which is supported in suitable bearings. The lower end of said vertical shaft is provided with a bevel wheel a which, meshing with a similar gear a on horizontal shaft or that is supported, in suitable bearings a suitable distance below the lower end of the horn socket 0; Secured to said shaft a is a crown wheel- (5 that gears with a pinion a on the lower end of a tubular vertical shaft a The pinion rests upon a support a which is bolted to the frame of the machine and it has a vertical stem a that has its bearing in said support. The tubular shaft a isconcentric with the axis of the rotary horn e and at its upper end is secured to the stem of a spur pinion a that has a bearing in the base of the horn and which pinion meshes with one member a of a train of gears a a and a the latter being supported close 11) to the normally inner side of the born Said pin ion a is secured to the lower end of the usual horn-whirl operating shaft a the whirl of known construction being of course located in the nose of the horn. The whirl and its driving shaft 0i being of known construction need not be further described. The ratio of the gearing described is such that the whirl maintainsin the known manner-a definite position, to ensure that the needle will receive the under thread in its barb, no matter to what position the horn may be rotated during the sewing operation.

If waxed thread is used, I provide, at a positi on well below the horn trunk and its socket, a wax-pot 0 having within it a guide roll 6 over which the thread T is passed. The thread then passes through a stripper e to remove excess wax then around a tension device 6 of suitable construction, thence through a thread lockto be described up through the horn socket and then over a guide roll 6 that is located high up in the wider part of the horn, these parts being so arranged that the position of the thread between the tension device and the guide roll 6 moves in a rectilineal path that is co-axial with the horn and its trunk.

After leaving the guide roll 6 the thread passes over a spring take-up roll c then over a roll carried on a main take-up lever e and from this to the whirl by way of a guide roll which may be the boss of the lever 0 on which the roll a is carried). As can be observed. from the drawing, the disposition of the lever e and the roll 6 relative to the whirl in the nose of the horn is such that when the main take-up lever is putting the final tension on the thread to set the stitch, namely when said lever is at its lowermost position, the thread leading from the roll or said lever to the whirl is only slightly bent, that is to say it forms a very obtuse angle as it passes over the guide roll e This is of importance as the less acute the angle to which the thread is bent the more rapidly can it be drawn tight enough to set the stitch without risk of breaking it, and the use of a vibrating take-up lever having its free end vibrating through an are about as shown, particularly lends itself to the attainment of the desirable result referred to.

Describing now these parts and their arrangement in greater detail, the thread lock comprises a post 6 carried by a bracket e which is secured to the frame of the machine, and on which post is mounted a sleeve 6 that slidable on said post and extends beyond it, the projecting end of the sleeve carrying a screw plug 6 between the adjacent ends of which plug and post the thread T is to be gripped at the appropriate moment so as to lock it when the take-up is in operation as is well understood. By rotating the plug in one or other direction itmay be adjusted nearer to or further from the post 6 A spring located on one side of a boss on the sleeve 6 tends to move the latter in the direction to remove the plug a from the end of the post 0 thereby releasing the thread, and to maintain the parts normally in its position to lock the thread, I provide a lever e mounted on a suitably sup ported stud e and having a downwardly projecting bifurcated arm which straddles and engages in the boss of the sleeve, 6. The arm 6 is provided with a cam roll e that is held in contact with the face of a cam block 0 on the shaft (657, the contact being maintained by the act-ion of the spring re ferred to on the sleeve 6 At a suitable position the face of the cam block 6 is formed with a cam recess 6 which momentarily permits the lever e to rock by the action of the spring referred to so that the plug 6 is moved away from the stud 6 thereby releasing the thread.

As already stated the thread passes upwards centrally through the trunk c and coaxially with the horn to the guide roll and from this over the auxiliary or take-up roll a". This roll is supported on a stud that is slidable in the lever 6 a spring 0 acting so as to tend to raise the said roll. From the roll 0 the thread passes over the roll on the main take-up lever 6 This lever mounted on a trunnion pin a that is supported comparatively high up within the horn and which lever is to be vibrated or rocked through an are about as indicated in Fig. 8.

In order to rock said lever I provide means comprising a pair of links such as a (one on each side of the lever 6 which. are pivotally connected at their upper ends to said lever and at their lower ends to a vertical tubular rod 6 that is concentric within the tubular shaft a and is guided top and bottom in bearings in the base of the horn and in the stem 64 of the pinion a. The lower end of said rod is provided with a yoke collar 6 with which the bifurcated end of one arm of a bell crank lever e engages. the other arm of which is provided with a cam roll that engages a cam race (2 in, the cam block 6 so that as said block rotates the rod 0 will be reciprocated in its bearings and through the links or connecting rods 6 the take-up lever will be'rocked through the angle about as shown.

By the construction of the parts described the main-take up may be brought comparatively close up to the whirl and its operation is effected by means not only extremely simple but also subject to the minimum of wear as the side strains are completely eliminated so far as regards the mechanism that is immediately concerned in bringing about its operation.

From the description already had it will be apparent that the needle thread passes up centrally through the tubular rod 6 and the take up lever is formed with a slot through which the thread passes on its way to the guide roll 0 The driving mechanism comprises the following The cam shaft a carries a loose pulley and clutch member combined 7 that will be driven by a belt (not shown) that also passes over the power driven pulley 72 (Fig. 1). Fixed to the cam shaft is the second clutch member f and a. spring f is provided that normally serves to separate the two clutch members 7, 7. The frictional engagement of the clutch members is effected in about the usual manner namely by pulling down or depressing a wedge 7 acting against a wedge block and ball thrust ring 7.

The stem of the wedge member f is secured by a set screw f to a cam or eccentric 7 projecting from a collar 7 that is rotatably mounted on a stud f projecting from a suitably supported slide member i to which latter a treadle rod f that is connected at its lower end to the usual treadle lever, is attached.

Mounted on the cam shaft a is a brake disc 7' and on the stud f is secured a brake shoe f that is acted on by a spring f so as normally to apply the brake and incidentally to maintain the treadle in its raised position. By depressing the treadle the downward movement of the stud f removes the brake and simultaneously draws down the wedge member f to start the machine.

In order that the machine shall stop at a definite predetermined point, the slide f is provided with a roll or equivalent f, and the boss of the bevel wheel a is formed as a cam so that at only one position of said boss can the roll 7 (and consequently the slide f and parts carried thereby) rise to allow the brake to be applied and the wedge device actuated to disconnect the clutch members.

It is desirable at times to rotate the cam shaft a by hand, and it is to permit this that the eccentric or cam projection f is provided on the rotary collar 7. Normally the collar is maintained in the position shown in Fig. 2 by a spring detent 7 which engages one of two notches or countersinks such as f. By turning the collar 7", by means of the handle shown, through an angle of 90 degrees, the cam or eccentric 7 will be turned and thus permit the said spring to lift the wedge member 7 to free the clutch members (the treadle being depressed by the workman to release the brake) the collar being retained by the spring detent engaging in the other one of the two notches, f.

The operation of the machine is as follows The needle thread having been passed up from the tension device through the thread lock to the take-ups in the horn is then threaded through the eye of the whirl and the end brought out on the surface of the horn tip. The shoe is then put over the horn, the presser foot being raised by means of the handle on the segment a.

The work being in positionthe workman permits the presser to be brought down into the channel or groove in the. work and when the machine is started the needle descends and its barb is threaded by the whirl while at the same time the presser foot is lifted and moved away from the needle a distance depending upon the length of the stitch required (this being determined by adjusting the throw of the bar a as described). The presser foot then descends firmly to engage the work whatever its thickness and the detent a will lock the presser (and feed foot). The needle next rises and at the appropriate moment the shut tle hookhaving a more or less chisel point engages the loop and this is thrown over the shuttle in the usual way, and in timed relation the needle dips permitting the shuttle to remove the thread from the barb of the needle and thereafter the loop is drawn down by the main take-up and the stitch completed.

Whilst this is occnringthe needle being still out of the workthe feed takes place by movement of the presser and feed foot in the reverse direction, and in order to avoid stopping the rotary movement of the shuttle until the needle has again descended and brought up another loop, the shuttle is moved away from the needle and is made to make an idle revolution whilst the needle is thus descending being brought back to the operative position again when the needle has brought up the next loop of thread.

By the construction described whereby a vibrating main take-up lever is brought comparatively vclose up to the. whirl and the thread extending between the main take-up and the whirl is bent to only a very obtuse angle, the machine may be run at a higher speed than machines of the type heretofore in use. The attainment of the said advantage is further assisted by guiding the. thread from a point well below the horn and its socket through the stem and up to a guide roll located fairly high up in the horn in a rectilineal path that is co-axial with the horn; and still further is the attainment of the desired object ensured by the very simple and direct acting means described and more or less directly associated with the main take-up lever to vibrate this latter.

Additional to the important improvements above referred to the arrangement of all details including the stitch forming mechanism, work feeding mechanism and driving mechanism constituting in combination with the aforementioned improvements the complete machine, also forms a very important feature of my invention.

What I claim is 1. A machine of the class described having, in combination, a standard, a horn socket, a rotary horn carried by said socket, thread guiding means to guide the thread through the socket and into the horn in a path coaxial with the horn, a slotted take-up lever within the horn supported on one side of and cross ing the path of the thread, a tubular thrust member connected up with said lever and extending from within the horn to below the socket, and means to reciprocate said thrust member.

2. A machine of the class described having a standard, a horn socket, a rotatable horn carried by said socket, thread guiding means to guide the thread coaxially with the socket and the born, a main take-up and a whirl within the horn, gear wheels also within the horn and connected up with the whirl, a tubular member passing through the socket coaxially therewith and into the horn and arranged. for reciprocating movement, means to reciprocate said member, a second tubular member also passing through the socket coaxially therewith and into the horn and arrangedt'or rotary movement, and means to rotate said second tubular member. 7

3. A machine of the class described having a standard, a vertical horn socl-zet, a rotary horn carried by said socket, stitch torming mechanism, a main take-up lever within the horn, a vertical reciprocating tubular member located coaxially with the horn, a link connecting said tubular member and said lever, thread guides to guide said thread through said tubular member and coaxial y with the horn, and means to reciprocate said member.

A machine of the class described having a standard, a vertical horn socket, a rotary horn carried by said socket, a wa-Xpot arranged for the passage therethrough of a thread and located below said socket, means to guide the thread from the waxpot into the horn coaxially with the socket and the horn, a main take-up lever and a whirl located within the horn, a tubular member extending axially through the socket and into the born, a link connecting said member and the takeup lever, a second tubular member also extending axially through the socket and into the born, a cam shaft, and connections be tween said shaft and said tubular members whereby reciprocating movement is imparted to the first and rotary movement to the second of said members.

5. A machine of the class described having, in combination, a horn socket, a rotary horn carried by said socket, a main take up and a whirl within the horn, a tubular thrust member adapted for vibration and extending through the socket into and coaxially with the horn, an operative connection between said thrust member and the take-up, a rotary tubular member also extending through the socket into and co-aXial with the horn, operative connections between said rotary member and the whirl, a main cam shaft, an auxiliary cam shaft, an operative connection between said shafts, a grooved cam on said auxiliary shaft, an operative connection between said cam and the thrust member, a crown wheel on said auxiliary cam shaft, and a bevel wheel 011 the rotary tubular member to gear with said crown wheel.

6. A lock-stitch sewing-1nachine having in combination a standard, a horn socket, a 1'0 tary horn carried by said socket, a main takeup lever and a whirl located within the horn, thread guiding means respectively within the horn and below the socket, a tubular thrust rod to impart vibratory movement to the take up lever, and a tubular shaft to impart rotary movement to the whirl, the said thrust rod and shaftbeing concentric with the horn and the guiding means located to guide the thread co-axially with the horn.

MARK THOMAS DENNE 

